1. Field of the Invention
The invention is directed to a Device for calibrating signals, whereby at least two signal circuits are provided for generating signals. The invention is also directed to a method for calibrating signals, whereby at least two signal circuits are provided for generating signals.
2. Description of the Related Art
Dynamic memories (DRAMs: Dynamic Random Access Memories) are tested with specific production test machines. Such a machine generates high-precision signals that are conducted to and applied to a memory component under test (DUT: Device under Test). A “high-precision signal” is a signal whose voltage level is very precisely set and that can be generated at precisely defined points in time. These production test machines likewise enable a precise detection of the signals generated by a DUT. I.e., specifically, these signals can be sampled at precisely defined points in time, read into a production test machine, and compared to comparison signals (what are referred to as the “anticipated signals”).
Clock frequencies up to 400 MHz are achieved given the technologies that are currently available in the DRAM field, e.g., RAMBUS or DDR (Double Data Rate) memories. Such memories require high-precision signals for testing whose specifications must currently be defined in a time range of approximately 500 ps. Shorter time ranges into a region of a few ps can be anticipated in future. These demands must be met by production test machines. An especially precise signal electronics is required for this purpose, but this produces very high costs.
Moreover, such production test machines usually make a plurality of independent input and output channels available that are at least partly programmable. These input and output channels are compared to an internal time reference of the machine and to data patterns generated in the machine. The input and output channels are therefore driven via complex pin cards with a plurality of ASICs (Application Specific Integrated Circuits) and electronic components. It is particularly the ASICs that cause very high costs since one ASIC is usually provided for each input and output channel; this ASIC is also referred to as “pin electronics”.